Poly(3-hydroxyoxetane), PHO, is an interesting analog of poly(vinyl alcohol) since it can be considered to be a copolymer of vinyl alcohol and formaldehyde. This polymer was first reported in very low molecular weight form by Wojtowicz et al (See: J. Org. Chem., 38, 2061 (1973) having been obtained from the spontaneous polymerization of 3-hydroxyoxetane, HO, although its structure was not established and no apparent utility existed for the reported substance. More recently, Vandenberg (See: J. Polym. Sci., Polym. Chem Ed., 23, 915 (1985) reported the preparation of low molecular weight branched PHO by a new base-catalyzed, rearrangement polymerization of glycidol and its trimethylsilyl ether. Further, using a pure enantiomer of glycidol, Vandenberg (supra) prepared low molecular weight, branched, isotactic PHO.
The present invention represents a further advance that it creates useful high molecular weight atactic and isotactic polymers of HO. As used herein, "Mw" means weight average molecular weight and "Mn" is number average molecular weight.
In the course of the work hereunder it was determined that the Wojtowicz et al spontaneous polymer was linear, low molecular weight (i.e., Mn&lt;2000, n.sub.inh of 0.05 or less), atactic, poly(3-hydroxyoxetane) (PHO) of high crystallinity and which after long storage at room temperature had --OCH.sub.2 CH(OH)CH.sub.2 OH end units. Spontaneous PHO apparently is formed by a cationic polymerization of HO by the carboxylic acids produced by the air oxidation of HO on standing at room temperature for several months. This polymerization can be duplicated by adding either 1-2% acetic acid or hydroxyacetic acid to HO.